I like Amsterdam Poppers. They give me a great rush. But, one thing I don't like about Amsterdam is that it seems to go stale rather quickly. I'd love to find some poppers that give a good rush but don't stale as quickly.

I've been using  Rush Black Label, Jungle Juice Black Label and English premium gold because it hits me hard and last a bit. Maximum Impact packs a wallop at least for me

Poppers vary depending on which country they are sold. In the UK you used to be able to buy butyl nitrite poppers, they had a good rush, but a few years ago they were banned. Since then isopropyl nitrite is sold as poppers in the UK and it is pretty hopeless. Recently some supplier are selling pentyl nitrite, but they don't seem too strong.

Amyl Nitrite, the original poppers, cannot be sold in the UK and apparently have a rush similar to butyl nitrite. Some guys use mail order personal import to get around the rules. I understand there are similar but different rules in the USA.

Keeping them cool and in a dark place slows down the process of going stale, but after they've been kept in a fridge /freezer let the sealed bottle warm to room temperature before opening otherwise condensation will get water in the mix and accelerate the degradation.

Maximum Impact and how to use it (very sparingly, as it turns out) is the topic of a thread here: https://breeding.zone/topic/5829-maximum-impact/. And seriously, a little bit sprayed on a rag and then breathing through the rag for 3-5 seconds was more than enough for me.

Is taking the cap off and exposing the poppers to the air what causes them to go stale? If so, would it work to pour the contents into, for instance, a perfume bottle with a vaporizer and administer them that way so that you never have to open the cap? Would that prolong their life? Or perhaps simply placing a piece of sponge or cotton or some other filter in the neck of the bottle? I assume the little ball in the bottle is because the contents stratify and need to be shaken up; is going 'stale' sometimes simply because the user hasn't shaken the bottle properly? Do you find that the larger quantity bottles go stale more quickly or more slowly than the smaller quantity bottles? That is, if you buy a bigger bottle, do you just have to use it up quicker so as not to waste your money?